The most common and most likely answer to this crossword clue is the 10 letter word ORDINARILY
O
R
D
I
N
A
R
I
L
Y
More clues leading to the result ORDINARILY
Buddy explains!

The straight part
We know that "as a rule" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case as a rule = ordinarily.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ORDINARILY mean?
ORDINARILY adverb- In accordance with normal custom or routine; as a matter of established occurrence.
- Usually or as a general rule; commonly.
- In the usual manner; unexceptionally.